Reference Values of Chemical Elements in the Hair of Children and Adolescents in the Western Region of the Republic of Kazakhstan

Aim: To establish reference intervals for chemical elements in hair samples of children and adolescents living in the Western region of Kazakhstan.Material and Methods: This cross-sectional study was conducted in the Western region of Kazakhstan, including the Aktobe, Mangistau, West Kazakhstan, and Atyrau regions. A total of 2,279 healthy children and adolescents (1,099 boys and 1,180 girls) aged 5 to <18 years participated in the study. Thirteen chemical elements were analyzed in hair samples: calcium (Ca), magnesium (Mg), zinc (Zn), selenium (Se), cobalt (Co), manganese (Mn), copper (Cu), iron (Fe), aluminum (Al), arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg). Hair element concentrations were determined using an Agilent 8900 ICP-MS. Reference intervals were established according to the International Union of Pure and Applied Chemistry (IUPAC) recommendations.Results: Reference intervals (95% reference intervals with 90% confidence intervals for the lower and upper limits) were established for all analyzed chemical elements in hair samples of healthy children and adolescents. Significant sex differences were observed, with boys having higher concentrations of Ca, Zn, Se, Co, Mn, Fe, Al, As, Cd, and Pb than girls.Conclusion: The reference intervals established in this study provide regional reference values for chemical element concentrations in children and adolescents living in Western Kazakhstan. The determined values may be used as a preliminary screening tool in assessing the impact of environmental factors, as well as in implementing preventive measures, providing necessary information and complementing other types of diagnostic procedures.